Foraging behaviour

We can tell a lot about our seabirds from what we can observe while they are at their nests on land. However, to get an insight into what they get up to when they are away from the colony, we need to use the latest electronic gadgets. This approach is sometimes referrred to as 'biologging'.

GPS Data Loggers

These devices receive signals from a network of orbiting satellites and record information on the position of the birds every two minutes. This allows us to track their movements as they fly away from the island on foraging trips. The map below shows examples of data from shags (2012) and kittiwakes (2011) with popular areas identified using Birdlife International's Marine Important Bird Area approach. Colours show where areas which are used by different proportions of the number of birds tracked (see keys for details). You can see that shags stay quite close to home, whereas kittiwakes range much farther afield.

We use relatively cheap and easily available 'IgotU data loggers. Click here for instructions on how to use these devices on seabirds.

Time Depth Recorders

Time depth recorders (TDRs) provide detailed information
concerning diving behaviour. By recording changes in pressure over time dive
profiles can be generated which provide information on factors such as dive
duration and dive depth. These devices are particularly useful on birds such as
shags which need to dive in order to capture their prey which largely occur
below the upper surface of the water column. On Puffin Island TDRs have been
successfully deployed on shags.

Accelerometers

Accelerometers are device which measure acceleration of the
body of an animal, ultimately giving a measure of movement. The accelerometers we use on Puffin Island are
tri-axial, recording across three axes, and as such give us detailed
information regarding the total movement of the birds. From the data collected
we can then determine the behaviour of the bird at any particular time when
carrying a logger. This is then useful in determining factors such as time
spent in flight, time spent resting at sea, time spent on the nest, and so on. Movement
is a significant source of energy expenditure and through quantifying movement
we can develop a clearer insight into the energetic costs our study species
face. To date these devices have been
successfully deployed on shags and kittiwakes on Puffin Island.